Synithetic lubricant compositions



SYNTHETIC LUBRICANT COMPOSITIONS Vernon W. David, Chester, and Fnnc'u H. Waight, Wirral, England, assignors to Shell Oil Company, a corporation of Delaware No Drawing. Filed Sept. '15, 1958, Ser. No. 760,867

8 Claims. (Cl. 252-484) The present invention relates to extreme pressure additives for aliphatic polyester synthetic lubricants and to synthetic lubricating compositions containing such additives. It relates more particularly to the use of certain chlorinated dimethanonaphthalene derivatives.

It is well known that the high pressures occurring in certain types of gears and bearings may cause a film of lubricant to rupture with consequent damage to machinery or engines. It has been shown that mineral oils can be improved with regard to their protective effect upon rubbing surfaces by the addition of a wide variety of certain substances so that excessive wear, scuffing, seizure and the like which normally follow a break in the film of lubricant can be prevented even under very unfavorable pressure and speed conditions. Lubricants possessing this highly desirable property are called extreme pressure lubricants. While many substances improve mineral lubricating oils in this respect, exceeding few compounds have been found which are effective for the same purpose when the lubricating oil is a synthetic material and particularly a polyester such as is formed between aliphatic dicarboxylic acids and monohydric alcohols. The need for such compositions is great, especially due to the advent of jet planes wherein synthetic lubricants are becoming a virtual necessity.

Many compositions which are useful for improving the extreme pressure properties of lubricants are those containing chlorine, sulfur and the like. However, the difficulty with most of these compounds, whether they are effective or not, is that they are thermally unstable and decompose to yield hydrochloric acid, H 8 and the like, which in turn cause corrosion and eventual failure of the metals with which they are in contact. This is true even of such materials as chlorinated terpenes, which are thermally unstable and readily yield hydrochloric acid upon heating. The presence of carboxyl groups in certain terpene-like compounds provides the opportunity for formation of esters of chlorinated terpenes. have virtually no extreme pressure properties when utilized in base lubricants to the extent of fractional percentages thereof and furthermore, have substantially no effect when dispersed in ester lubricants, as will be shown a by means of comparative data given hereinafter.

It is an object of the present invention to provide improved lubricating compositions. It is a further object of this invention to provide improved aliphatic polyester lubricants. It is a'particular object of the present invention to provide aliphatic polyester lubricant compositions showing surprisingly effective extreme pressure properties. Other objects will become apparent during the following description of the invention.

Now, in accordance with the present invention, it has been found that extreme pressure lubricating compositions are provided by dispersal of between about 0.2 and about 10% by weight of l,2,3,4,l0,lO-hexachloropolyhydro-dimethanonaphthalenes and/or their corresponding 6,7- epoxy, episulfido, or epi-imino derivatives, said dimethano- However, such materials r 2,971,913 Patented Feb. 14, 1961 naphthalene derivatives being dispersed in aliphatic polyester lubricants.

The small group of compounds utilized in connection with the aliphatic polyesters may be either endo, endo; endo, exo; or exo, exo variations of the same type of molecule since the spacial configuration with respect to the plane in which the individual radicals exist does not appear to affect their utility in the present compositions. Any of the above varieties are suitable. The species otherwise designated (other than with respect to their spacial configurations) are as follows:

1,2,3,4,10,10 hexachloro 1,4,4a,5,8,8a-hexahydromethanonaphthalenes 1,2,3,4,10,10-hexachloro 6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydrodimethanonaphthalenes 1,2,3,4,10,10 hexachloro-6,7-episulfido 1,4,4a,5,6,7,8,8a-

octahydrodimethanonaphthalenes 12,3,4,l0,10 hexachloro-6,7-imino-1,4,4a,5,6,7,8,8a-octahydrodimethanonaphthalenes The following four species defined still further with respect to their spacial configuration are those particularly preferred for use in the subject compositions:

1,2,3,4,l0,10 hexachloro 1,4,4a,5,8,8a-hexahydro-endol,4-exo-5,S-dimethanonaphthalene 1,2,3,4,10,l0 hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo-l,4-exo-5,B-dimethanonaphthalene 1,2,3,4,10,10 hexachloro 1,4,4a,5,8,8a-hexahydro-endol,4-endo-5,8-dimethanonaphthalene 1,2,3,4,10,10 hexachloro-6,7-epoxy 1,4,4a,5,7,8,8a-octahydro-endo-I,4-endo-5,S-dimethanonaphthalene The aliphatic polyester lubricants may be generally classed as diesters, tetraesters and polyesters having a greater number of ester linkages. Typical of the diester lubricants are those formed between aliphatic dicarboxylic acids having from 4 to-12 carbon atoms per molecule with monohydric alcohols having from 6 to 18 carbonatoms per molecule, the esters containing between about 16 and 40 carbon atoms per molecule. Typical species include bis(Z-ethylhexylJsebacate, bis(2-ethylheptyl) adipate and didecylazealate. Esters based on pentaerythritol are also contemplated, which may be esters formed between aliphatic monocarboxylic acids and pentaerythritol or may be esters formed with a dimer of pentaerythritol. Typical species include especially those in which a mixture of fatty acids is utilized for the formation of the esters since the resulting ester mixture has a substantially lower melting point or pour point than that obtained if a single acid is utilized. Single species include pentaerythritol tetracaproate, pentaerythritol tetravalerate, pentaerythritol tetraheptoate, pentaerythritol dicaproate divalerate, pentaerythritol tricaproate heptoate and mixtures thereof. The dimers of pentaerythritol include dipentaerythritol hexacaproate, dipentaerythritol hexavalerate and mixed esters, such as dipentaerythritol tricaproate triheptoate. ployed.

Of course, mixtures of'esters may be em- EXAMPLE I The lubricating oil employed was a synthetic diester oil being a blend of base esters consisting of 70% by weight of dinonyl sebacate, 20% by weight of dio'ctyl sebacate and 10% by weight of dinonyl adipate. Test samples were prepared by adding the chlorine-containing compounds to be tested to the base esters to give concentrations equivalent to 1% by weight of chlorine based on the weight of the lubricating oil. I.A.E. gear rig tests were performed on the base esters plus aldrin and for the sake of comparison with the base esters alone and base esters plus dioctyl chlorendate. The tests were done at 2,000 r.p.m. and at 60 C. Two tests were performed on each oil, using 4-pint samples at tit-pint per minute flow rate and the results of these tests are given in Table I. The results showed that the dioctyl chlorendate had no beneficial effect on the extreme pressure characteristics of the base esters whereas aldrin and hexachlorocyclopentadiene were effective in improving the extreme pressure characteristics of the base esters.

Table I Mean scuffing load in lbs. Base esters 58 Base esters+1,2,3,4,l0,10 hexachloro 1,4,4a,5,8,8a-

hexahydro-endo-1,4-exo-5,S-dimethanonaphthalene- 75 Base esters+dioctyl chlorendate 50 EXAMPLE II The base esters in this example were the same as those described in Example I.

The I.A.E. gear rig tests described in Example I were repeated at different temperatures with base esters plus aldrin, and for the purposes of comparison, with base esters alone and base esters plus dimethyl chlorendate. The results of these tests are given in Tzible II. The results showed that aldrin was effective in improving the extreme pressure characteristics of the base esters and was more eifective in this respect than dimethyl chlo- The base esters in this example were the same as those described in Example I. The I.A.E. g'ear rig tests described in Example I were repeated at different temperatures with base esters plus dieldrin and for the purposes of comparison, with base esters alone and base esters plus dimethyl chlorendate. The results of these tests are given in Table III. The results showed that dieldrin was effective in improving the extreme pressure characteristics of the base esters and was more effective in this respect than dimethyl chlorendate. The tests in this example were performed at 4000 r.p.m.

Compositions of this invention may contain minor proportions of other lubricating oil additives, such as antioxidants, corrosion inhibitors or anti-rusting compounds, wear reducing agents, blooming agents, pour point depressants, viscosity improvers and anti-foaming agents.

Anti-oxidants which may be used comprise several types, for example, alkyl phenols, such as 2,4,6-trimethyl phenol, pentaethyl phenol, 2,4-dimethyl-6-tertiary-butyi phenol, 2,4-dimethyl-6-octyl phenol, 2,6-ditertiary-butyl- 4-methyl phenol and 2,4,6-tritertiary-butyl phenol, amino phenols, such as benzyl amino phenols and amines-such as dibutylphenylene diamine, diphenylamino, N-phenylbeta-naphthylamine, N-phenyl-alpha-naphthylzirnine' and dinaphthylamine.

Examples of suitable corrosion inhibitors or anti-rusting compounds which may be used are the dicarboxylic acids having 16 or more carbon atoms in the molecule and organic compounds containing acidic radicals in close proximity to a nitrile, nitro or nitroso group, for example, alpha cyano stearic acid.

Wear reducing agents which may be used comprise esters of phosphorus acids, such as triaryl, alkaryl or aralkyl phosphates, thiophosphates or phosphites' and neutral aromatic sulfur compounds of relatively high boiling point, such as diaryl sulfides, diaryl disulfides, alkyl aryl disulfides, for example, diphcnyl sulfide, diphenol sulfide, dicresol sulfide, dixylenol sulfide, methyl butyl diphenol sulfide, dibenzyl sulfide and the corresponding diand tri-sulfides. v r,

As an example of a suitable anti-foaming agent dimethyl silicone polymer can be mentioned. Additional ingredients may comprise oil-soluble urea or thiourea derivatives, for example, urethanos, allophanates, carbazides and carbazcne, polyisobutylene polymers and polymerized unsaturated esters of fatty acids and 'monohydric alcohols.

One of the advantages gained by the use of the present invention especially when the epi derivatives of dimethanonaphthalene are employed is the surprisinglylow corrosion caused by the compositions. Even though the recited class of chlorinated dimethanonaphthalene is abnormally stable under high temperature conditions, nonetheless any chlorinated compound can be expected to release at least trace amounts of chlorine-or chlorine derivatives. These can be expected to be, corrosive in nature andhence it is preferred practice to provide for a chlorine acceptor such as an epoxide or similar compounds. Thus, it will be seen by a study-.of the compounds involved in the present compositions that'a builtin chlorine acceptor is present within the molecule. When the epi compounds are employedeitheras the sole extreme pressure agent or in addition to'one-of theother dimethanonaphthalene chlorinated compounds with which the present invention is concerned. This feature distinguishes the present compositions from those knownin the prior art in that the extreme pressure'agent-may also constitute a chlorine'acc'eptor if the latter is released during the use of the compositions involved.

We claim as our invention: 1. A lubricating composition comprising a major proportion of dinonyl sebacate and between about 0.2% and about 10% by weight of. 1,2,3,4,10,10-hexachlorol,4,4a,5,8,8a-hexahydrocndo-1,4 eXo 5,8 dimethanonaphthalene.

2. A lubricating composition comprising a major proportion of dinonyl sebacate and between about 0.2% and about 10% by weight of 1,2,3,4,l0,l0-hexachloro- 6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro endo -'1,4-exo-5 .8- dimethanonaphthalene. I

3. A lubricating composition comprising a major proportion of dinonyl sebacate and between about'0.2% and about 10% by weight of l,2,3,4,10,10-hexachloro- 1,4,4a,5,8,8a-hexahydro-endo-1,4-endo 5,8 dimethanonaphthalene.

4. A lubricating composition comprising a major proportion of dinonyl sebacate and between about 0.2% and about 10% by weight of 1',2,3,4,l0,l0-hexachloro- 6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro endo l,4-endo- 5,8-dimethanonaphthalcne.

5. A lubricating composition comprising a major. proportion of an'oleaginous ester of an aliphatic dicarboxylic acid and an aliphatic monohydric alcohol, said ester containing between about 16 and 40 carbon atoms per molecule and between about 0.2% and about 10% by weight of an unsubstituted 1,2,3,4,10,10-hexachloro-L4,

4a,5,8,8a-hexahydro-1,4,5,8'dirnethanonaphthalene.

6. A lubricating composition comprising a major proportion of an oleaginous ester of an aliphatic diearboxylic acid and an aliphatic monohydric alcohol, said ester containing between about 16 and 40 carbon atoms per molecule and between about 0.2% and about 10% by weight of an unsubstituted 1,2,3,4,10,10-6,7-epoxyhexachloro-1,4,4a,5,6,7,8,8a-octahydro 1,4,5,8-dimethanonaphthalene.

7. A lubricating composition comprising a major proportion of an oleaginous ester of an aliphatic dicarboxylic acid and an aliphatic monohydric alcohol, said ester containing between about 16 and 40 carbon atoms per molecule and between about 0.2% and about 10% by weight of a chlorinated dimethanonaphthalene of the group consisting of 1,2,3,4,10,10-hexachloro-I,4,4a,5,8, 8a-hexahydro-1,4,5,8-dimethanonaphthalenes, 1,2,3,4,10, 10-hexachloro-6,7-epi-1,4,4a,5,6,6,7,8,8a-octahydro 1,4,

5,8-dimethanonaphthalenes, wherein epi is an epatomic 20 radical of the group consisting of epoxy, episulfido and epi-imino, and mixtures thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,635,979 Lidov Apr. 21, 1953 FOREIGN PATENTS 451,411 Great Britain July 29, 1936 453,047 Great Britain Aug. 31, 1936 OTHER REFERENCES Lubrication Engineering, August 1952, pp. 177-179. 

8. A LUBRICATING COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OLEAGINOUS ALIPHATIC POLYESTER LUBRICANT OF THE GROUP CONSISTING OF ALIPHATIC DIESTERS AND ESTERS OF PENTAERYTHRITOL AND BETWEEN ABOUT 0.2% AND ABOUT 10% OF A CHLORINATED DIMETHANONAPHTHALENE OF THE GROUP CONSISTING OF 1,2,3,4,10,10-HEXACHLORO-1,4,4A,5,8,8A-HEXAHYDRO - 1,4,5,8 - DIMENTHANONAPHTHALENE, 1,2,3,4,10,10-HEXACHLORO-6,7-EPI-1,4,4A,5,6,6,7,8,8A-OCTAHYDRO - 1,4,5,8 - DIMETHANONAPHTHALENES, WHEREIN EPI IS AN EPATOMIC RADICAL OF THE GROUP CONSISTING OF EPOXY, EPISULFIDO AND EPI-EMINO, AND MIXTURES THEREOF. 